The present invention relates to power tools and, more particularly, to motors for power tool flux rings with anchors to retain molded magnets on the flux ring.
In motor construction, the motor magnets must be retained on the housing or separate flux ring within the housing. Ordinarily, these magnets have been glued or adhered to the metallic ring or housing. In adhering the magnets to the metallic surface so that the magnets do not shift during use, various types of adhesives have been used. While some of the adhesives have been satisfactory, some adhesives work better than others. As the adhesives age, it is possible that if the power tool is dropped, that the sudden shock will destroy the bond between the magnet and the housing or ring, enabling the magnet to travel within the motor. When this occurs, the motor ceases to function. Thus, it would be desirable to provide a mechanism to retain the magnets in position on the ring or housing.
The present invention provides the art with a mechanism to retain magnets onto a flux ring or motor housing. Due to the advent of molded magnets, it is possible to provide an anchor in the flux ring or housing to retain the molded material on the ring or housing. One such anchoring member is an aperture having a counter-sink on the exterior of the ring or housing. Thus, when the magnet is molded onto the ring, the magnetic material that passes through the ring into the counter-sink forms a solid rivet-shaped fastener. Also, anchors may be stamped out of the ring or housing and project into the interior of the ring to receive the molded magnetic material. The anchors include gussets to reinforce the bend points to enhance the strength of the anchors and help resist deformation during molding. Due to the anchors being unitarily formed or stamped from the ring or housing, an aperture is left in the ring or housing after stamping, which is likewise filled with the molded magnetic material.
In accordance with a first aspect of the invention, a flux ring comprises an annular housing. At least one molded magnet is received on the housing. An anchor on the housing retains the at least one magnet on the annular housing. The anchor is unitarily formed with the housing. The anchor includes at least one bend. A reinforcement member is positioned at the bend to strengthen the anchor. The annular housing is metal with the anchor projecting radially from the housing. The projecting anchor has an aperture immediate the anchor on the housing. Thus, the magnetic material molds around the anchor and into the aperture. The anchor may have several different shapes. Preferably, the anchor has a rectangular shape, with one or both ends connected to the housing. Also, the anchor may have an L- or T-shape with one end connected to the housing.
In accordance with a second aspect of the invention, a motor comprises a stator assembly with the stator assembly including a flux ring. The flux ring comprises an annular housing. At least one molded magnet is received on the housing. An anchor on the housing retains the at least one magnet on the annular housing. The anchor is unitarily formed with the housing. The anchor includes at least one bend. A reinforcement member is positioned at the bend to strengthen the anchor. The annular housing is metal with the anchor projecting radially inward from the housing. The projecting anchor has an aperture immediate the anchor on the housing. Thus, the magnet molds around the anchor and into the aperture. The anchor may have several different shapes. Preferably, the anchor has a rectangular shape, with one or both ends connected to the housing. Also, the anchor may have an L- or T-shape with one end connected to the housing. Also, the motor comprises an armature rotatable within the stator assembly. A commutator is rotatable with the armature and connected to the armature via a shaft. A brush assembly is associated with the commutator.
In accordance with a third aspect of the invention, a power tool comprises a housing with a motor in the housing. The motor comprises a stator assembly with the stator assembly including a flux ring. The flux ring comprises an annular housing. At least one molded magnet is received on the housing. An anchor on the housing retains the at least one magnet on the annular housing. The anchor is unitarily formed with the housing. The anchor includes at least one bend. A reinforcement member is positioned at the bend to strengthen the anchor. The annular housing is metal with the anchor projecting radially inward from the housing. The projecting anchor has an aperture immediate the anchor on the housing. Thus, the magnet molds around the anchor and into the aperture. The anchor may have several different shapes. Preferably, the anchor has a rectangular shape, with one or both ends connected to the housing. Also, the anchor may have an L- or T-shape with one end connected to the housing. Further, the anchor may have a truncated cone shape with an axial aperture through the cone. Also, the motor comprises an armature rotatable within the stator assembly. A commutator is rotatable with the armature and connected to the armature via a shaft. A brush assembly is associated with the commutator. Also, the power tool includes an output member coupled with the motor shaft. An actuator member is electrically coupled between the motor and the power source to energize and de-energize the motor. In turn, when the motor is energized, the output member rotates.
Additional objects and advantages of the present invention will become apparent from the detailed description of the preferred embodiment, and the appended claims and accompanying drawings, or may be learned by practice of the invention.